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Old 11-04-2014, 07:42 PM   #15
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So if you get an MB update, the chip has to be sent back to RennTech to reinstall it?
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Old 11-05-2014, 05:59 AM   #16
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So if you get an MB update, the chip has to be sent back to RennTech to reinstall it?
Yeah. But as I said, MB is well aware that I have the RennTech tune, since Mercedes Benz of Baton Rouge removed the chip to have the tune done in the first place and reinstalled it when the work was done. I don't think they'd reprogram the chip back to MB defaults unless there was a major flaw in quality control in the MB service department.
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Old 11-10-2014, 07:07 PM   #17
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2013.5 DO NOT apply ECU update

I had my follow up appointment with the Atlanta Mercedes dealership today regarding the speedometer issue. I was not at all surprised that they had done zero research in the two weeks since, despite me telling them at least one other person in this forum confirmed a speedometer issue after that update.

After 4 hours of applying, test driving, applying again, no joy. I'm told they are creating something called a PTSS. I don't remember the acronym but it basically means they don't know nothing about birthin no babies and Mercedes engineering has to figure out. But they assure me they will be right back to me in a jiffy with the fix. Right.

They also assure me there isn't anything else that could be causing harm to my vehicle with this update, even though I'm getting 14 mpg going 55 on the highway. Maybe that is a simple math error from the speed calculation being off. Who knows.

But here is my advice and maybe it will help others: I would strongly recommend refusing this update if you have a 2013.5 model Interstate! Not only will I be shocked if my speedometer isn't still off a year from now, but the shift points are very different and the RV feels slow to accelerate, sluggish, and not nearly as peppy as it was before.

Brian
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Old 11-10-2014, 07:14 PM   #18
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I will make dealer visit this week. They are currently working on my SLK and I don't want to confuse them.
These guys are pretty good in wanting me happy, just hope we get it figured out. Maybe 2 PTSS's will get some attention. If they fix it, I'll pass the info on.



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Old 11-10-2014, 07:17 PM   #19
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PTSS stands for Product Technical Support System report.


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Old 03-20-2015, 05:45 PM   #20
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Quick update...it took 4 months but Germany finally issued a bulletin to Mercedes dealers about this update causing the speedometer issue. I had to leave it there for two days, but they input something they called an SCN code to fix it back to original.

Will be nice to see something above 15 mpg again.
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Old 03-21-2015, 12:16 PM   #21
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I had the ECU update done last week

What does actually consist of?

And was this speedometer issue updated with the last week?


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Old 03-21-2015, 04:51 PM   #22
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This is not accurate. The feature you describe (called "Selective Availability") is technically possible, but was discontinued in May of 2000 at the direction of President Clinton. The next generation of GPS will not even have this feature.

GPS.gov: Selective Availability
Position accuracy is irrelevant in determining speed which is calculated from the Doppler shift in the GPS carrier wave.
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Old 03-21-2015, 05:20 PM   #23
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Just so you are aware, GPS is government controlled satellite navigation supported for military use. Therefore the signal, hence accuracy can vary significantly from day to day, hour to hour, etc. I don't know that I would expect my GPS to be more accurate than my vehicle on any given day.
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This is not accurate. The feature you describe (called "Selective Availability") is technically possible, but was discontinued in May of 2000 at the direction of President Clinton. The next generation of GPS will not even have this feature.
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Position accuracy is irrelevant in determining speed which is calculated from the Doppler shift in the GPS carrier wave.
Mostly but not entirely true. A GPS computes its position several times a second. When you first fire up the GPS while your vehicle is at a standstill in Park, the GPS is calculating the same position over and over, and can get a very accurate fix. When you start moving, your previous position versus your new position is used in the speed computation - but so is the doppler shift from the movement of the various satellites it's tracking. And every time you come to a stoplight or a stop sign, the GPS again has a chance to calculate the same position over and over and get a more accurate fix.

The speed indicator on your automotive GPS will be accurate to about half a mile per hour, more accurate if you're on flat terrain so there's no real elevation change factored in.

For the sake of safety— and for moving-violation avoidance— you should always assume that if you see multiple speed indications— analog dial, digital readout in the message center, and/or GPS— whichever one shows the highest speed is right. The highest indicated speed may not actually be right, but assume it is and drive accordingly.
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Old 04-21-2015, 07:36 AM   #24
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Finally got my AI in to correct the speedometer error introduced by the ECU update last Fall. Now it's a waiting game, while I raid the big bowl of peppermint patties my dealer keeps in the waiting area. Seem to have won the mouse-war I discovered when I go t the van out of storage. Getting ready for a run to the east coast and then up into Michigan.


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Old 04-21-2015, 06:36 PM   #25
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All's well that ends well

They "re-coded" my Sprinter's ECU update. Success.....my speed is now accurate and my gas mileage is back to reading normal consumption rates. Now ready to hit the road again.....
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